Shim help required please

munckee · September 2021

I think my jaguar could do with a shim since fitting a staytrem, I can lower the bridge but to get a decent break angle I think it needs a shim to set it up right. I bought some cheap ones from amazon which are steel and go over the rear two neck screw holes to raise the angle.

I've since read that it is likely the shim will indent into the neck and I should use a full pocket shim.

firstly is that right and secondly can I do that with card or do I need to get a wood version, and how complicated is that to make sure it fits the heel.

Thanks as always

Funkfingers · September 2021

munckee said:

I've since read that it is likely the shim will indent into the neck and I should use a full pocket shim.

A steel shim is harder than ash, alder, basswood or maple. Hence, yes, it will indent the wood. Use something less hard.

WezV · September 2021

It probably won't be an issue at all. Some guitars get a bit of a hump from a shim, but its rarer than the Internet would have you believe.

Full pocket shims work when you need a big change to angle. For most guitars a strip of card or veneer works absolutely fine and compresses nicely in the join. Metal is OTT, but if everything is tight it will still work fine

ICBM · September 2021

I would use card or fibreboard, as Fender did. It's soft enough to compress and deform to the surfaces of the wood and not the other way round. I also sometimes use wood veneer. I don't personally believe the type of material has any bearing on 'tone', and every time I've removed a full-pocket shim (because it was the wrong angle) and replaced it with a normal small one, the guitar has sounded better afterwards. Although that could be just because it was set up better...

munckee · September 2021

Thanks think I will try cardboard first to be on the safe side.

BillDL · September 2021

I use a bit of rough sandpaper for shims. It doesn't compress like cardboard does and there are so many rough bits that aren't pronounced enough to make indentations in wood. The roll of 2 inch wide emery tape I use is about 0.5mm thick. If that isn't enough I have some mahogany veneer that is about 0.75mm thick, or else I will double up the sandpaper. Start thin and increase the thickness in very small increments until you get it just right. It's a pain having to keep taking the neck back off, but as long as you are careful to get the screws back into the right threads in the neck and don't overtighten them, you aren't increasing the wear and tear by doing so.

There are arguments that say if you only put a shim at the very back of the neck pocket that covers only about one eighth of the length of the pocket, that it can pull the unsupported part of the neck heel downwards into the hollow, deforming it, or that it can allow moisture into the gap that swells the neck heel. First of all a wooden shim would absorb more moisture than a lacquered neck heel. Unless you are using a fairly thick shim, the hollow that these people speak of is absolutely miniscule and you probably get more wood movement from natural expansion and contraction taking the guitar out of its case into the different environment of a room than any effects caused by the unsupported hollow where the neck heel doesn't have a shim between it and the pocket. 1970s Fenders had a micro-tilt mechanism instead of having to shim. I never had any problems with my 1979 Strat in the two decades that I owned it.

It is possible to calculate how much the neck angle will be increased by for a given thickness of shim using trigonometry. In fact, Dan Erlewine's American based StewMac sells their wooden full pocket shims by degrees of taper rather than by thickness.

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Shim help required please

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